Urodynamic Tests

What is a urodynamic test?

This is the name for a test performed as an outpatient to determine how the bladder works. It takes about one hour to do. The aim is to understand the activity of the bladder whilst it is filling with urine and during activity. To do this, a very narrow tube has to be passed into the bladder through the urethra. The procedure is usually well tolerated. Sometimes, it is combined with x-rays and is known as videourodynamics. Local anaesthesia may be used, but not general anaesthesia. Pressures are measured in the rectum (the 'back passage') at the same time through a separate tube.

This test is also known as videourodynamics, pressure flow studies or cystometrogram.

Why am I having this test?


The test can determine the cause of urinary symptoms such as:

  • urine leakage (incontinence) that occurs on activity (e.g. coughing, lifting, sneezing, laughing) or without activity but associated with an urgent desire to pass urine
  • increased frequency of passing urine during the day and night
  • slow flow, stopping and starting, and the need to dribble to finish passing urine

It can also help predict whether drugs or surgery are likely to have a good result for;

  • stress incontinence in women
  • overactivity of the bladder (also known as detrusor instability or overactivity)

What should I do before this test?

It is not necessary to fast the night before or take laxatives. As long as the urine test is normal, the study is very safe and can be performed with minimal discomfort. It is important to arrive with a full bladder since it may be necessary to pass urine into a special machine ("urinary flow rate test") before the formal urodynamic test and for a test by the nurse to determine if an infection is present. Usually, a nurse and an x-ray technician will be in the room during the test.

If you are having a period (menstruating), it is still possible to perform the test, but it may be more comfortable to delay the test to a day when you are not.

If you are taking medication such as Detrusitol (tolterodine), Lyrinel (oxybutynin), Regurin (trospium), propiverine, or solifenacin (Vesicare), please stop these about 1 week before the test. Continue taking other medication including aspirin, clopidogrel (Plavix) and warfarin unless you are told otherwise. You can restart them after the test. If you are not sure whether you should stop these drugs, please ask your doctor first. This is especially important if you are taking Yentreve (duloxetine) and you should not stop this drug without discussing with your doctor how to do it.

What will happen during the test?

You will need to undress and put on a gown. Local anaesthetic jelly will be placed in the urethra (the water-pipe from the bladder). A narrow tube (catheter) will be placed by a doctor or nurse through the urethra ('water pipe') into the urinary bladder. In addition, another narrow tube will be placed in the rectum (the 'back passage'). The study can be performed standing or sitting. A computer will record all of the measurements and produce a record of the events during the test.

Your doctor may be present during the study or later when the results are available for analysis. He will evaluate and interpret the study based on the recordings and x-ray tests if they have been performed.

What happens after the test?

Half an hour after the test, you will be able to go home. You may experience some burning when passing urine for a few days and this is normal. There may be some blood in the urine, but as long as large clots are not formed, the bleeding will settle if you drink plenty of fluid. You can resume regular diet, medications, and normal activity levels after you leave.

Antibiotics are often prescribed for three days afterwards.

Your results and their analysis will be discussed in a clinic in outpatients.